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Patterns of distribution and environmental correlates of macroalgal assemblages and sediment chlorophyll a in Oregon tidal wetlands
Citation:
JANOUSEK, C. N. AND C. FOLGER. Patterns of distribution and environmental correlates of macroalgal assemblages and sediment chlorophyll a in Oregon tidal wetlands. JOURNAL OF PHYCOLOGY. Allen Press, Inc., Lawrence, KS, 48:1448-1457, (2012).
Impact/Purpose:
Algae have important functional roles in estuarine wetlands along the Pacific coast of the United States.
Description:
Algae have important functional roles in estuarine wetlands along the Pacific coast of the United States. We quantified differences in macroalgal abundance, composition and diversity, and sediment chlorophyll a and pheophytin a among three National Wetlands Inventory emergent marsh classes in four Oregon estuaries spanning a range of riverine to marine dominance. We also assessed the strength of macroalgal-vascular plant associations and the degree to which environmental variables correlated with algal community metrics across all marsh and woody wetlands sampled. The frequency of occurrence of most macroalgal genera, total benthic macroalgal cover, macroalgal diversity, and sediment chlorophyll a content were several times higher in low emergent marsh than in high marsh or palustrine tidal marsh. Conversely, pheophytin a: chl a ratios were highest in high and palustrine marsh. Attached macroalgae (Fucus and Vaucheria) were strongly associated with plants common at lower tidal elevations such as Sarcocornia perennis and Jaumea carnosa; Ulva (an unattached alga) was not strongly associated with any common low marsh plants. In step-wise multiple regression models, intertidal elevation and soil salinity were the most influential predictors of macroalgal cover and richness and chlorophyll a. Though common taxa such as Ulva spp. occurred across a broad range of salinities, wetlands with oligohaline soils (salinity < 5) had the lowest macroalgal diversity and lower sediment chlorophyll a. These types of baseline data on algal distributions are critical for evaluating the structural and functional impacts of future changes to coastal estuaries including sea-level rise, altered salinity dynamics, and habitat modification.
